Any electrical whizzes out there? Over my head with wiring

[gomotomoto]

My 64 ambassador was restored by a certified auto mechanic. He wasn't the worst, but he wasn't winning any prizes for great/clean work either. Ran into a problem that i need a hand with:

Today, I ran #8 wire from the back of the trailer to the front to power my jack. I grounded the battery to the frame. Jack works great.

There are two other sets of existing duplex wires that go to the battery. I am not sure, but I think one set is for a battery charger and the other goes to the electrical panel and powers the DC side of the trailer.

I tested the jack to the battery alone, worked perfectly. When I added the two sets of duplex wires to the battery terminals, one of the eyelets sparked and got red hot. I checked in the panel and two blade fuses had blown.

Anyone know what would cause this to happen?

[SteveH]

A duplex outlet is normally wired for 120VAC, not 12volt DC. Therein lies your problem, me thinks.

[J. Morgan]

You need to see where the existing wires go in order to find the problem and the solution, otherwise it is all a crap shoot.


Brevi tempore!

[J. Morgan]

He may well have run two positives in a single duplex wire and two negatives in the other....

Or maybe all of the wires are positive.....

You really need to find the other ends of the wires.


Brevi tempore!

[Al and Missy]

Originally Posted by SteveH

A duplex outlet is normally wired for 120VAC, not 12volt DC. Therein lies your problem, me thinks.

The OP was talking about duplex wires which usually refers to a red and black pair inside one jacket.

Al

[kb0zke]

One tool that might help is a two-part device. One part is put near one end of a wire and sends a signal through that wire. The other part is moved around close to where the other end of the wire ought to be. When it sounds off you have found the other end of the wire. I'm having a senior moment right now and can't think of the proper name of this thing. They aren't real cheap, but not very expensive, either.

As always, it is safest if all electricity (12 vdc and 120 vac) is disconnected.

[richinny]

Originally Posted by kb0zke

One tool that might help is a two-part device. One part is put near one end of a wire and sends a signal through that wire. The other part is moved around close to where the other end of the wire ought to be. When it sounds off you have found the other end of the wire. I'm having a senior moment right now and can't think of the proper name of this thing. They aren't real cheap, but not very expensive, either.

As always, it is safest if all electricity (12 vdc and 120 vac) is disconnected.

something like this?:Cable Tracker

[kb0zke]

Yes!

[HowieE]

Was the trailer plugged into shore power when you connected the wire to the battery?

I can't see how you could have blown fuses if you were just working with 12 volts.

You had a dead short and will have to inspect ALL wiring for melted insulation before you go forward.

Pictures might help.

[SuzyHomemakr]

Number one thing: Don't just hook stuff up to your battery! That's what your fuse panel is for. The manual for your jack should have a good suggestion about what size fuse and wire you should be using.

I've got a custom install of a Xantrex inverter/charger, so it's probably very different from what you have. There should be some sort of big master fuse between the battery bank and the 12V panel, and maybe even a big cut-out knife switch in there, as well. That would help to prevent a welding experiment like you described from burning the trailer down.

There are wiring diagrams available for most models of Airstream, check the web for a download. Airstream does some oddly creative wiring, so sometimes logic is not your best friend when troubleshooting. They also use somewhat undersized wire IMO, which is more easily damaged.

My tips:
Isolate your circuits and test them.
Know what wire goes where, and that the wires are of proper size.
Look for any kind of damage, however slight, and fix it.
Verify that you have good power at both ends of the circuit
Assume that any previous assumption you made is wrong.
Curse loudly and often, it's a good stress reliever.

Remember the Geek Code: If you ask for help, you are required to report the solution to all that you asked, so that the complexity of the universe will be diminished!

[cwf]

Oops, you let out the magic smoke...

Need to update this thread or folks move on to important things...

[68 TWind]

Unhook everything at the battery and make a long jumper wire for your multi meter. I made one about 25 ft long with alligator clips on each end.
Set the meter to continuity and then it is easy to find the other end of the wires by just probing with the tip of the lead.
Label everything and make a drawing. On my 68 there are two leads on each battery post, one from the charger/converter and the other runs to the DC control panel. In 68 the DC box was behind the "Central Control" panel over the fridge. I'm sure yours is different but you get the idea. I checked every wire in my trailer, both AC and DC using this method and made a diagram. Helped me figure it all out and then a few months later the drawing kept me from having to do it all over again when I wired in the AC box (short memory).
Good luck.

[gomotomoto]

Thanks all. Using most of the tips above, I was able to find a few stupid issues that resolved the problem. One wire was the culprit.

[cwf]

12vdc short or miswired?